1. Field of the Invention
The present invention relates to manufactured composite board products wherein the composite board product is a compressed, heat treated mixture of natural fibrous material, resin and wax.
2. Related Art
Manufactured composite board products, typically wafer board, hard board, oriented strand board, particle board, medium density fiberboard, etc., have been produced for many years and their method of manufacture is well known in the industry.
Typically such board products are produced by using a natural fibrous material as the primary component which is then sprayed, dipped or otherwise combined with a minor amount of resin and slack wax, formed into sheets and subjected to pressure and heat to yield finished, thin, generally stiff sheets of manufactured board materials.
U.S. Pat. No. 4,404,252 describes a surface stabilized waferboard having at least one surface rendered water resistant and stabilized against water loss.
In the process of that patent a wafer board is produced by bonding together wood wafers, adhesive resin and wax in a hot press, the water resistance and surface stabilization of at least one surface being accomplished by bonding a layer of porous paper to at least one surface of the wafer board while the wood wafers are being bonded together in the hot press. The wax employed in producing the wafer board is an aliphatic petroleum product referred to generally as a slack wax and is used in an amount in the range of 1 to 2 wt % of the wafer board, based on the oven dry weight of the wafer board.
While not so recited in the literature the slack wax generally used in the production of manufactured wafer or fiber board is typically 30 grade slack wax (550 N) which typically has an oil content in the range 18-28 wt %, more usually 18-21 wt % oil. A 10 grade slack wax (150 N) has also been used and it has a typical oil content in the range 12-28 wt %, more usually 14-21 wt %.
"The Effect of Wax Type and Content on Waferboard Properties" Hsu, et al, International Particleboard/Composite Materials Symposium, 1990, pp. 85-93, discusses and addresses the effect of wax content and oil content in wax on the physical properties of waferboard. The paper addresses waferboard swelling in response to from zero to 4.5% wax content as well as waferboard swelling and internal bond strength in response to from 0 to 30 wt % oil content in the wax used in the production of the waferboard.